@magalss It looks like libqsqlmysql.so takes libmysqlclient.so from /usr/lib/... not from /usr/local/lib.
If you want to use the one from /usr/local/lib you will need to add the path to LD_LIBRARY_PATH
You can try to set QT_DEBUG_PLUGINS=1 before starting your app - you then should see some debug output which can help to find the issue (see http://doc.qt.io/qt-5/debug.html).